A conventional magnetic resonance imaging apparatus applies a readout gradient magnetic field to a gradient coil when acquiring magnetic resonance signals. A readout gradient magnetic field needs to be applied to a gradient coil at a constant intensity. However, depending on a transient response from the gradient coil, a waveform of the readout gradient magnetic field may be distorted. In this case, a phase of an acquired magnetic resonance signal (a phase of a nuclear magnetization of spin) may be distorted; in other words, a coordinate point of a magnetic resonance signal that is arranged in k-space may be shifted.
For example, radial scanning is known as a scanning method that has robustness against subject's movements. Magnetic resonance signals in the radial scanning is, however, susceptible to phase distortion, because magnetic resonance signals are acquired from a low-frequency region in the k-space with the radial scanning.
As a method of solving such phase distortion, a method of correcting phase distortion using pre-scanning and a method of calibrating phase distortion when a magnetic resonance imaging apparatus is installed, are known.